Composition and method for detergency of asphalt soil



United States Patent 3,462,369 COMPOSITION AND METHOD FOR DETERGENCY OF ASPHALT SOIL Abraham Mankowich, Bel Air, Md., assignor to the United States of America as represented by the Secretary of the Army No Drawing. Filed Oct. 24, 1966, Ser. No. 589,121

Int. Cl. Clld 1/83 U.S. Cl. 252-138 9 Claims ABSTRACT OF THE DISCLOSURE A detergent composition for removing asphalt soil comprising a powder mixture of from about 88 to about 92 percent by weights of alkaline salts to provide a pH of about 12 in solution and from about 8 to about 12 percent by weight of a surfactant combination consisting of from about 1:1 to about 1:10 ratios by weight of a nonionic silicone surfactant selected from the group consisting of silanes and siloxanes, and an anionic surfactant selected from the group consisting of sodium lauryl sulphate and sodium dodecylbenzene sulphonate.

The invention described herein may be manufactured and used by or for the Government, for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to an improved composition and method for removing asphalt soil from surfaces. More specifically, it relates to an aqueous alkaline cleaner which exhibits a remarkable effectiveness in deterging asphalt soil rapidly and completely.

It is known in the metal cleaning art that organic solvents and various organic cleaners which contain surface active agents, emulsifiers, dispersants and other additives are capable of removing asphalt. Organic solvents and cleaners, however, present health hazards and further increases in time and labor costs due to the need for mechanical action which is usually necessary in removing the more resistant asphaltic type contaminations. I have made the discovery that an aqueous cleaner may be formulated with effective detergency action, one that can be utilized to better advantage for removing asphalt, tars, rust preventive compounds, heavy grease, and the like, and that produces clean surfaces with greater ease as compared with previous organic or aqueous type cleaners.

It is therefore the prime object of my invention to provide an aqueous type cleaner that removes surface contamination from metals and other surfaces rapidly and completely. Another object of the invention is to provide improved detergency in a cleaning solution as demonstrated by its ability to remove the more resistant asphaltic contamination. Advantages of the present composition over organic-based asphalt cleaners are (1) increased personnel safety, (2) increased economy of operations and (3) improved cleaning. The improved cleaning achieved by the present composition may be further emphasized from the fact that the present aqueous composition produces chemically clean surfaces whereas organic solvents leave the surfaces only physically clean, necessitating soaking solutions to bring the surfaces to the desired degree of cleanliness.

In the method of the present invention, the surfaces to be cleaned, and from which it is desired to remove all traces of asphalt, are brought into contact with an alkaline solution of ca. pH 12 containing from about 5 to about 12 ounces per gallon, preferably from about 9 to about 11 ounces per gallon, of a mixture of alkaline salts. The solution also contains a specific combination ice of surfactant compounds comprising from about 8 to about 12 percent by weight of the total additives in solution, preferably at about 11 percent by weight, of a nonionic silicone surfactant and an anionic surfactant, which may be either sodium lauryl sulphate or sodium dodecylbenzene sulphate. The nonionic and anionic surfactants are present in solution in weight ratios of about 1:1 to about l:l0,'respectively. After the surfaces are stripped of all adhering asphalt, they are then washed free of cleaning solution.

The composition as formulated for packaging and shipping contains dry granules or a powder mixture of alkaline salts and builders including sodium metasilicate, trisodium phosphate, primary sodium phosphate and sodium sulphate together with the sodium lauryl sulphate (or sodium dodecylbenzene sulphonate) and the silicone compound which will now be described and identified in suflicient detail. The silicone which is in liquid form is included in the mixture as a thin film coating on the granules or powder particles therein.

The silicone compounds which have been found useful as the nonionic surfactant in accordance with the invention are organosilanes and organosiloxanes which are distinguished by the presence of an organic chain of recurring oxyalkalene unit. The preferred organic chain is predominantly of ethoxy units forming ethoxylated organosilicones with average molecular weight of about 400-550.

Ethoxylated silanes which may be used in the practice of this invention can be represented by the following general formula:

wherein R is a monovalent hydrocarbon radical and a has a value from 0 to l; R may be a hydrogen atom or a saturated hydrocarbon radical; n is an integer with a value of at least one, and Ethoxy may have a chain of 2 units.

Illustrative of specific silicone surfactants with the above configuration are:

[CH3(OC2H4) s z zlz 3) 2 4 onxooinmoonzompsi (C2H4O)H Ethoxylated methyl silicones which may be used as the nonionic surfactant may be represented by a general formula as follows:

wherein R is a monovalent hydrocarbon radical and R and R" are chain-terminating monovalent aliphatic radicals; y is an integer having a value of 2; x is an integer having a value of at least 5 and denotes the length of the oxyethylene chain; a and b are integers whose sum is 2 or 3. The composition of the siloxanes are for the most part mixtures of polymers wherein x and y are of different values and that methods of determining the chain length of the polysiloxane and polyoxyethylene give values which represent average chain lengths.

When the polysiloxane is a dimer, the structural formula will be as follows:

Illustrative of specific siloxanes having the above structural configuration are the following:

The length of the organic chain contributes to the solubility properties of the surfactants. Increasing the number of oxyethylene units will vary the solubility from a water-insoluble product to a water-soluble product. In general, average molecular weights in the range of about 400 to about 550 are found to exert a significant effect on the detergent properties of the cleaning solutions. Organosilanes and organosiloxanes suitable for use as the silicone surfactant described in this specification are disclosed in US. Patents 3,172,899 and 2,917,480.

Commercially available silicone liquids of the type described above are designated at L-76 and L-77 and are manufactured by Union Carbide Corporation, New York. These ethoxylated methyl silicone liquids are suitable for use as the nonionic surfactant component of the present composition as disclosed herein. These liquids exhibit the following properties on analysis.

Soluble Properties Water solubility, percent 5102, percent Viscosity, kinematic at 25 0. (cs) Surface tension at 25 C. (dynes/cm. of a 0.1%

solution) Cloud point, C

safely with aluminum and its alloys which can withstand a moderate alkalinity. The cleaning operation is carried out most effectively by immersion in boiling solution.

EXAMPLE II Ingredient: Percent by weight Na SiO 32.8 Na PO 25.7 NaH PO 19.9 lqazsoq Sodium dodecylbenzene sulphonate 9.3

ASPHALT REMOVAL TEST The detergency action or effectiveness of the present composition as compared with similar compositions in which each surfactant compound is used singly on a comparable level is illustrated in the table below. Test solutions were prepared in which the alkaline salt content was identical in each case. Equal surfactant content was also employed in these solutions. In samples 1-3 the test solution contained a single surfactant composition in equal quantities by weight. In samples 47 the surfactant were utilized in combination in various weight ratios as prescribed herein.

The asphalt removal test was made on steel panels which were coated on one face with a petroleum asphalt conforming to Federal Specification SS-A-706, grade 85-100, designation AP-S. The steel panels measured 2 /2 inches square of 18-20 gauge and 330 milligrams of petroleum asphalt was coated on the surface. The asphalt coated panels Were immersed in boiling, 10 ounces per gallon, aqueous solutions, allowed to remain therein for a designated period of time and then withdrawn and rinsed with water. The percentage of asphalt removed was determined gravimetrically.

TABLE.PERCENT BY WEIGHT Anionic surfactant Silicone surfactant Sodium Sodium Alkaline salts Immersion Percent dodecylbenzene lauryl time, asphalt L-67 11-77 sulphonate sulphate N 3 304 NaaSlO.5H:0 N83P04J2H50 NaHIPOLHQO minutes removed None None 11. 1 8. 9 34. 5 33. 5 12. 0 21 None 11. None None 8. 9 34. 5 33. 5 12. 0 21 None 8. 9 34. 5 33. 5 12. 0 21 None 8. 9 34. 5 33. 5 12. 0 7 100 8. 9 34. 5 33. 5 12. 0 7 100 8. 9 34. 5 33. 5 12. 0 17 100 8. 9 34. 5 33. 5 12.0 21 90 The following examples illustrate the present composition both as a dry mixture and in the form of a solution as formed at the time of use.

The above dry mixture is dissolved in water to form a solution of about 10 ounces per gallon. The solution is then heated and maintained at a temperature preferably above 80 C. in removing asphalt and other contamination from metallic, ceramic, glass objects and the like. The alkaline mixture formulated to provide an alkalinity not exceeding about a pH 12 in solution may be used The silicone surfactants used in carrying out this test were the ethoxylated products which display average molecular weights of approximately 400-550.

The comparison test illustrates the efficacy of the present surfactant combination in removing asphalt when neither one of these surfactant compounds displays any ability to remove asphalt when used alone for this purpose. Asphalt removal is, of course, a measure of the deterging ability of this surfactant combination and is indicative of the increased effectiveness of the present composition as an aqueous bath cleaner.

In the foregoing description I have disclosed preferred embodiments of my invention. However, it is not intended that this invention be limited to the specific examples set forth above, as it is apparent to those skilled in the art, that the proportions of the ingredients may be varied and a variety of equivalent substances may be employed without departing from the spirit of the invention or exceeding the scope of the appended claims.

Having thus described the invention, what is claimed as new and desired to be secured by United States Letters Patent is:

1. A detergent composition for removing asphalt soil comprising a powder mixture of from about 88 to about 92 percent by weight of alkaline salts selected from the group consisting of: Na SiO -5H O; Na PO -12H O; NaH PO -H O, and Na SO to provide a pH of about 12 in solution, and from about 8 to about 12 percent by weight of a surfactant combination consisting of from about 1:1 to about 1:10 ratios by weight of a nonionic silicone surfactant having a molecular weight of 400-500 selected from the group consisting of:

wherein R is a methyl radical, R is selected from the group consisting of a hydrogen atom and a methyl radical, a has a value of to 1, and n is an integer with a value of at least 1, and;

wherein -R is a methyl radical,

R and R" are selected from the group consisting of methyl and butyl radicals,

x is an integer having a value of at least 5,

y is an integer having a value of two, and

a and b are positive integers whose sum is 2 to 3, and an anionic surfactant selected from the group consisting of sodium lauryl sulphate and sodium dodecylbenzene sulphonate.

2. A detergent composition as in claim 1 in which water is included to form a solution of from about to about 12 ounces of the detergent composition per gallon of Water.

3. A detergent composition as in claim 1 in which said nonionic silicone surfactant has the following configuration:

4. A detergent composition as in claim 1 in which said nonionic silicone surfactant has the following configuration:

5. A detergent composition as in claim 1 in which said nonionic silicone surfactant has the following configuration:

6. A detergent composition as in claim 1 in which said nonionic silicone surfactant has the following configuration:

References Cited UNITED STATES PATENTS 3,198,747 8/1965 Cook et al 252-156 X LEON D. ROSDOL, Primary Examiner P. E. WILLIS, Assistant Examiner US. Cl. X.R. 2521 5 6, 161 

